1. Field of the Invention
This invention relates to a camera having a mechanism for changing the frame of its photographic image plane from one frame over to another.
2. Description of the Related Art
At present, the photographic image plane frames of cameras are mostly arranged to be in a sidewise long shape measuring 24.times.36 mm for a 35 mm silver-halide film which is placed in a film cartridge and is most prevalent among other types of silver-halide films. In addition to this sidewise long shape (hereinafter referred to as the normal size), there are other image plane frame sizes including a half size which is vertically long and a panorama size which is much longer sidewise. To avoid a confusion at photofinishing, developing laboratories, it has been practiced to arrange the camera of the kind using the film of the above-stated size to permit taking shots all at the same size of the photographic image plane frame for the whole of one roll of film by inhibiting change-over of the image plane frame from one size to another after the back lid of the camera is closed. However, printing a photograph in the panorama size has recently become very popular. As a result, a camera which is arranged to permit easy manual selection from outside between different photographic image plane frames has come to be desired. Some cameras that are arranged to meet this requirement have already been manufactured.
A lens shutter type camera has nothing within a space between the film surface and a photo-taking lens. Therefore, a mask for change-over from one photographic image plane frame to another can be retractively arranged immediately before the film surface without difficulty. On the other hand, in the case of a single-lens reflex camera, it is very difficult to arrange such a mechanism because of a quick-return mirror which is arranged in front of the film surface.
Therefore, the conventional single-lens reflex camera has been arranged to permit change-over between different photographic image plane frames only by mounting an adapter in the rear of the shutter after opening the back lid of the camera.
However, with the photographic image plane frame change-over arranged to be effected by means of the adapter like in the case of the conventional single-lens reflex camera, it is impossible to permit the change-over by an external (manual) operation while one roll of film has not been completely used for taking shots. One roll of film, therefore, must be used for shooting with one and the same photographic image plane frame.
Another problem with the adapter mounting type change-over arrangement lies in that the change-over operation is troublesome as it necessitates the work of mounting the adapter on the camera. Besides, some arrangement is necessary for stowing the adapter when it is not in use. This has presented a further problem.